1. Field of the Invention
The present invention relates to a writing instrument having a mechanism for transforming rotation of the rear tubular member into axial displacement of a writing tip.
2. Background Information
In the prior art, the writing tip of a writing instrument, for example a ball-point pen can be extended or retracted in response to direction of rotation of a rear tubular member of the writing instrument. The writing instrument can be used when the writing tip extends outward from a front tubular member of the writing instrument.
In mechanical pencils of prior art, after the writing tip is extended outward from a front tubular member of the pencil in response to rotation of a rear tubular member of the mechanical pencil, a lead advancing mechanism is activated by a knock operation so that a lead projects from the writing tip, and then the pencil can be used.
In ball-point pens of the prior art, there is the problem of the mechanism for transformation of rotation and axial displacement presenting a mechanically complicated structure. Also in mechanical pencils of the prior art, there is the problem that they not only need the mechanism for transformation of rotation and axial displacement but also need a lead advancing mechanism to be activated by a knock operation, thereby the construction becomes further complicated. Further they need both a rotation operation and knocking operation, thus they lack simplicity and costs are increased.